Publications by authors named "Dennis Litty"

New drugs are needed to combat multidrug-resistant tuberculosis. The electron transport chain (ETC) maintains the electrochemical potential across the cytoplasmic membrane and allows the production of ATP, the energy currency of any living cell. The mycobacterial engine F-ATP synthase catalyzes the formation of ATP and has come into focus as an attractive and rich drug target.

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The FF-ATP synthase is required for the viability of tuberculosis (TB) and nontuberculous mycobacteria (NTM) and has been validated as a drug target. Here, we present the cryo-EM structures of the Mycobacterium smegmatis F-ATPase and the FF-ATP synthase with different nucleotide occupation within the catalytic sites and visualize critical elements for latent ATP hydrolysis and efficient ATP synthesis. Mutational studies reveal that the extended C-terminal domain (αCTD) of subunit α is the main element for the self-inhibition mechanism of ATP hydrolysis for TB and NTM bacteria.

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Hyperthermophilic archaea are close to the origin of life. Some hyperthermophilic anaerobic archaea live under strong energy limitation and have to make a living near thermodynamic equilibrium. Obviously, this requires adaptations of the energy-conserving machinery to harness small energy increments.

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Acetogenic bacteria such as Acetobacterium woodii use the Wood-Ljungdahl pathway (WLP) for fixation of CO and energy conservation. This pathway enables conversion of diverse substrates to the main product of acetogenesis, acetate. Methyl group containing substrates such as methanol or methylated compounds, derived from pectin, are abundant in the environment and a source for CO .

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Methanol is one of the most widely produced organic substrates from syngas and can serve as a bio-feedstock to cultivate acetogenic bacteria which allows a major contribution to reducing greenhouse gas. Acetobacterium woodii is one of the very few acetogens that can utilize methanol to produce acetate as sole product. Since A.

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While many bacteria are able to bypass the requirement for oxidative phosphorylation when grown on carbohydrates, is unable to do so. Differences of amino acid composition and structural features of the mycobacterial F-ATP synthase (α:β:γ:δ:ε::::) compared to its prokaryotic or human counterparts were recently elucidated and paved avenues for the discovery of molecules interfering with various regulative mechanisms of this essential energy converter. In this context, the mycobacterial peripheral stalk subunit δ came into focus, which displays a unique N-terminal 111-amino acid extension.

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Mycobacteria regulate their energy (ATP) levels to sustain their survival even in stringent living conditions. Recent studies have shown that mycobacteria not only slow down their respiratory rate but also block ATP hydrolysis of the F-ATP synthase (α:β:γ:δ:ε::::) to maintain ATP homeostasis in situations not amenable for growth. The mycobacteria-specific α C-terminus (α533-545) has unraveled to be the major regulative of latent ATP hydrolysis.

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Eubacterium limosum KIST612 is one of the few acetogenic bacteria that has the genes encoding for butyrate synthesis from acetyl-CoA, and indeed, E. limosum KIST612 is known to produce butyrate from CO but not from H  + CO . Butyrate production from CO was only seen in bioreactors with cell recycling or in batch cultures with addition of acetate.

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ATP synthases are the key elements of cellular bioenergetics and present in any life form and the overall structure and function of this rotary energy converter is conserved in all domains of life. However, ancestral microbes, the archaea, have a unique and huge diversity in the size and number of ion-binding sites in their membrane-embedded rotor subunit c. Due to the harsh conditions for ATP synthesis in these life forms it has never been possible to address the consequences of these unusual c subunits for ATP synthesis.

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A A ATP synthases with a V-type c subunit have only been found in hyperthermophilic archaea which makes bioenergetic analyses impossible due to the instability of liposomes at high temperatures. A search for a potential archaeal A A ATP synthase with a V-type c subunit in a mesophilic organism revealed an A A ATP synthase cluster in the anaerobic, acetogenic bacterium Eubacterium limosum KIST612. The enzyme was purified to apparent homogeneity from cells grown on methanol to a specific activity of 1.

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Despite their key role in numerous natural compounds, β-amino acids have rarely been studied as substrates for microbial degradation. Fermentation of the newly isolated Paraburkholderia strain BS115 and the type strain P. phytofirmans PsJN with β-phenylalanine (β-PA) as sole nitrogen source revealed (S)-selective transamination of β-PA to the corresponding β-keto acid by both strains, accompanied by substantial formation of acetophenone (AP) from spontaneous decarboxylation of the emerging β-keto acid.

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